What does mystery( ) do? public class Roster { private ArrayList list = new ArrayList(); public Student mystery(){ Student student1 = list.get(0); double gpa = student1.getGPA(); for(int i = 1; i < list.size(); ++i) { Student s = list.get(i); if(s.getGPA() > gpa) { student1 = s; } } return student1; } } Returns the student with the highest GPA Always returns the first student in the roster Returns the student with the lowest GPA Sorts the student list by GPA